[repoter maven] Fix SLF4j binding warning when unit testing 
[repoter maven] Fix SLF4j binding warning when unit testing 

Add a SLF4j implementation with a test scope (using the managed slf4j-simple dep). 
Signed-off-by: Clément Delgrange <5b5d4f1bb51b8e82b6a088d12648e7597cd70738@protonmail.com>
psoreide/bnd,psoreide/bnd,psoreide/bnd